public class Pillar {
   Geometry bottom;
   double height;
   Pillar (Geometry bottom,double height) {
     this.bottom=bottom;
     this.height=height;
   }
   public double getVolume() {
     if(bottom==null) {
       System.out.println("没有底,无法计算体积");
       return -1;
     }
     return bottom.getArea()*height;
  }
} 
